diff --git a/media/sctp/sctptransport.cc b/media/sctp/sctptransport.cc
index 42780f0e69..41d4b7a0c5 100644
--- a/media/sctp/sctptransport.cc
+++ b/media/sctp/sctptransport.cc
@@ -46,8 +46,8 @@ namespace {
 // take off 80 bytes for DTLS/TURN/TCP/IP overhead.
 static constexpr size_t kSctpMtu = 1200;
 
-// The size of the SCTP association send buffer.  256kB, the usrsctp default.
-static constexpr int kSendBufferSize = 262144;
+// The size of the SCTP association send buffer. 256kB, the usrsctp default.
+static constexpr int kSendBufferSize = 256 * 1024;
 
 // Set the initial value of the static SCTP Data Engines reference count.
 int g_usrsctp_usage_count = 0;
diff --git a/pc/channelmanager.cc b/pc/channelmanager.cc
index 522f19736c..23abdefb59 100644
--- a/pc/channelmanager.cc
+++ b/pc/channelmanager.cc
@@ -58,12 +58,6 @@ void ChannelManager::Construct(std::unique_ptr<MediaEngineInterface> me,
 ChannelManager::~ChannelManager() {
   if (initialized_) {
     Terminate();
-    // If srtp is initialized (done by the Channel) then we must call
-    // srtp_shutdown to free all crypto kernel lists. But we need to make sure
-    // shutdown always called at the end, after channels are destroyed.
-    // ChannelManager d'tor is always called last, it's safe place to call
-    // shutdown.
-    ShutdownSrtp();
   }
   // The media engine needs to be deleted on the worker thread for thread safe
   // destruction,
diff --git a/pc/srtpfilter.cc b/pc/srtpfilter.cc
index fbea08fdc5..5f581f3826 100644
--- a/pc/srtpfilter.cc
+++ b/pc/srtpfilter.cc
@@ -25,13 +25,6 @@
 
 namespace cricket {
 
-// NOTE: This is called from ChannelManager D'tor.
-void ShutdownSrtp() {
-  // If srtp_dealloc is not executed then this will clear all existing sessions.
-  // This should be called when application is shutting down.
-  SrtpSession::Terminate();
-}
-
 SrtpFilter::SrtpFilter() {
 }
 
diff --git a/pc/srtpfilter.h b/pc/srtpfilter.h
index ffdf637ae9..556d89a6b6 100644
--- a/pc/srtpfilter.h
+++ b/pc/srtpfilter.h
@@ -33,8 +33,6 @@ struct srtp_ctx_t_;
 
 namespace cricket {
 
-void ShutdownSrtp();
-
 // A helper class used to negotiate SDES crypto params.
 // TODO(zhihuang): Find a better name for this class, like "SdesNegotiator".
 class SrtpFilter {
diff --git a/pc/srtpsession.cc b/pc/srtpsession.cc
index ba49b166ae..4ba3619d9c 100644
--- a/pc/srtpsession.cc
+++ b/pc/srtpsession.cc
@@ -10,20 +10,16 @@
 
 #include "pc/srtpsession.h"
 
-#include "third_party/libsrtp/include/srtp.h"
-#include "third_party/libsrtp/include/srtp_priv.h"
 #include "media/base/rtputils.h"
 #include "pc/externalhmac.h"
+#include "rtc_base/criticalsection.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/sslstreamadapter.h"
+#include "third_party/libsrtp/include/srtp.h"
+#include "third_party/libsrtp/include/srtp_priv.h"
 
 namespace cricket {
 
-bool SrtpSession::inited_ = false;
-
-// This lock protects SrtpSession::inited_.
-rtc::GlobalLockPod SrtpSession::lock_;
-
 SrtpSession::SrtpSession() {}
 
 SrtpSession::~SrtpSession() {
@@ -31,6 +27,9 @@ SrtpSession::~SrtpSession() {
     srtp_set_user_data(session_, nullptr);
     srtp_dealloc(session_);
   }
+  if (inited_) {
+    DecrementLibsrtpUsageCountAndMaybeDeinit();
+  }
 }
 
 bool SrtpSession::SetSend(int cs, const uint8_t* key, size_t len) {
@@ -300,7 +299,11 @@ bool SrtpSession::SetKey(int type, int cs, const uint8_t* key, size_t len) {
     return false;
   }
 
-  if (!Init()) {
+  // This is the first time we need to actually interact with libsrtp, so
+  // initialize it if needed.
+  if (IncrementLibsrtpUsageCountAndMaybeInit()) {
+    inited_ = true;
+  } else {
     return false;
   }
 
@@ -323,10 +326,15 @@ void SrtpSession::SetEncryptedHeaderExtensionIds(
   encrypted_header_extension_ids_ = encrypted_header_extension_ids;
 }
 
-bool SrtpSession::Init() {
-  rtc::GlobalLockScope ls(&lock_);
+int g_libsrtp_usage_count = 0;
+rtc::GlobalLockPod g_libsrtp_lock;
 
-  if (!inited_) {
+// static
+bool SrtpSession::IncrementLibsrtpUsageCountAndMaybeInit() {
+  rtc::GlobalLockScope ls(&g_libsrtp_lock);
+
+  RTC_DCHECK_GE(g_libsrtp_usage_count, 0);
+  if (g_libsrtp_usage_count == 0) {
     int err;
     err = srtp_init();
     if (err != srtp_err_status_ok) {
@@ -345,22 +353,21 @@ bool SrtpSession::Init() {
       LOG(LS_ERROR) << "Failed to initialize fake auth, err=" << err;
       return false;
     }
-    inited_ = true;
   }
-
+  ++g_libsrtp_usage_count;
   return true;
 }
 
-void SrtpSession::Terminate() {
-  rtc::GlobalLockScope ls(&lock_);
+// static
+void SrtpSession::DecrementLibsrtpUsageCountAndMaybeDeinit() {
+  rtc::GlobalLockScope ls(&g_libsrtp_lock);
 
-  if (inited_) {
+  RTC_DCHECK_GE(g_libsrtp_usage_count, 1);
+  if (--g_libsrtp_usage_count == 0) {
     int err = srtp_shutdown();
     if (err) {
       LOG(LS_ERROR) << "srtp_shutdown failed. err=" << err;
-      return;
     }
-    inited_ = false;
   }
 }
 
diff --git a/pc/srtpsession.h b/pc/srtpsession.h
index 2d4dd6f121..94702da130 100644
--- a/pc/srtpsession.h
+++ b/pc/srtpsession.h
@@ -74,9 +74,6 @@ class SrtpSession {
   // been set.
   bool IsExternalAuthActive() const;
 
-  // Calls srtp_shutdown if it's initialized.
-  static void Terminate();
-
  private:
   bool DoSetKey(int type, int cs, const uint8_t* key, size_t len);
   bool SetKey(int type, int cs, const uint8_t* key, size_t len);
@@ -87,7 +84,14 @@ class SrtpSession {
   // Returns send stream current packet index from srtp db.
   bool GetSendStreamPacketIndex(void* data, int in_len, int64_t* index);
 
-  static bool Init();
+  // These methods are responsible for initializing libsrtp (if the usage count
+  // is incremented from 0 to 1) or deinitializing it (when decremented from 1
+  // to 0).
+  //
+  // Returns true if successful (will always be successful if already inited).
+  static bool IncrementLibsrtpUsageCountAndMaybeInit();
+  static void DecrementLibsrtpUsageCountAndMaybeDeinit();
+
   void HandleEvent(const srtp_event_data_t* ev);
   static void HandleEventThunk(srtp_event_data_t* ev);
 
@@ -95,7 +99,7 @@ class SrtpSession {
   srtp_ctx_t_* session_ = nullptr;
   int rtp_auth_tag_len_ = 0;
   int rtcp_auth_tag_len_ = 0;
-  static bool inited_;
+  bool inited_ = false;
   static rtc::GlobalLockPod lock_;
   int last_send_seq_num_ = -1;
   bool external_auth_active_ = false;